Control System For Panel Heating

ABSTRACT

A control system for panel heating, in particular in the form of underfloor heating systems. In said system a respective valve controls the volumetric flow of hot water through the panel heating of a room and a valve, which divides the volumetric flow of hot water that is supplied to the respective room into two parts, is positioned upstream or downstream of the first valve. The first part of the volumetric flow of hot water is supplied to the panel heating directly or via a restrictor unit, while the second part of the volumetric flow of hot water is supplied to the panel heating via a thermostatically regulated control valve.

The invention relates to a control system for panel heating of the typementioned in the precharacterizing clause of claim 1.

In recent years, panel heating, especially in the form of floor heatingbut also in the form of heated ceilings and walls, has been becomingever more important. The advantages of economical and energy-savingoperation, better room-air hygienic conditions, comfort and futuristic,environmentally friendly low-temperature systems are also beingexploited in multiple occupancy houses.

The lawmakers have defined specific regulations for the control systemof a heating installation. The law controls:

-   -   1. The heating water temperature and    -   2. The heating-water volume flow

The heating-water temperature (inlet temperature) is controlled asstandard via a central control system for the entire building, by meansof the outside temperature and/or another reference variable.

As is likewise stipulated by the lawmakers, the heating-water volumeflow is controlled by means of automatically acting devices forcontrolling the room temperature, on a room-by-room basis.

The control valve which is influenced by the “room air temperature”reference variable varies the heating-water volume flow with the aim ofvarying the heat emitted from the panel, for example in the floor, tothe room.

In the case of panel heating, the type of room-by-room temperaturecontrol that is known for space heaters using the room temperature as areference variable, by virtue of the lack of any alternative, is notdirectly suitable, since panel heating reacts too slowly for thispurpose. The floor fittings which are normally used in modern floorheating systems result in variation of the heat output becomingeffective only after about 2 hours. This time between the action of thecontrol valve and the start of effectiveness in the room is referred toas the control time or delay time. This also applies to panel heaters inthe form of heated walls and ceilings.

This disadvantageous effect of this delay time is ameliorated by thephysical phenomenon known as the “self-regulation effect”. This naturaleffect regulates the power output from the heating panel in directproportion to the temperature difference between the heating-paneltemperature and the room temperature. This effect, which has a verypowerful effect because of the small temperature difference especiallywith panel heating, is independent of control systems and takes place atthe same time as changing room-temperature conditions. This reduces thepoor, slow response of the control valve.

The invention is based on the object of providing a control system ofthe type mentioned initially, which has an improved control response.

This object is achieved by the features specified in claim 1.

Advantageous refinements and developments of the invention are specifiedin the dependent claims.

The invention is based on the discovery that, if the amount of heatwhich must be supplied to the room in accordance with the calculatedheat load in order to reach the required room temperature is analyzed, adistinction must be drawn between by far the majority of the heat whichmust be supplied permanently and a small component which is influencedby external influences such as solar radiation, external heat, fans etc.

If these disturbance-variable influences did not exist, then it would besufficient to match the inlet temperature to the outside temperature forthe entire building. There would be no need for additional room-by-roomcontrol.

The proportion of the heating-water volume flow which corresponds to thepermanently supplied amount of heat should not be influenced by aslow-reaction control valve.

In the control system according to the invention, the heating-watervolume flow is split by a valve in a freely variable ratio into twovolume flow elements, in which case each volume flow element can beinfluenced by at least one different type of controlled variable. Thesetwo volume flows may be varied between 0 and 100%, with the first partof the heating-water volume flow being supplied directly to the panelheating, while the second part of the heating-water volume flow issupplied to the panel heating via a thermostatically controlled controlvalve.

In one embodiment, the valve is designed such that it allows theproportional components of the first part of the heating-water volumeflow, which is supplied directly to the panel heating, and of the secondpart of the heating-water volume flow, which is supplied via thethermostatically controlled control valve, to be adjusted.

In this case, the valve can permanently set the proportional componentof the first and second part of the heating-water volume flow, or theproportional components of the heating-water volume flow may beadjustable.

In the first case, the valve may have a fixed shutter which governs thesecond part of the heating-water volume flow which is supplied to thepanel heating.

In the second case, the valve may itself have an adjustment capabilityfor the magnitude of the two volume-flow elements, or a furtheradjusting valve for the first part of the heating-water volume flowwhich is supplied directly to the panel heating can be arranged betweenthe valve and the inlet of the panel heating.

In one embodiment, the valve may be remotely controllable both for thefirst part and for the second part of the heating-water volume.

The valve which controls the overall heating-water volume flow may be anadjusting or shut-off valve for hydraulic regulation of all of the panelheating in a heating installation, and precedes or follows the valvewhich controls the ratio of the two volume flow elements.

According to one preferred refinement of the invention, the valve whichcontrols the ratio of the two volume flow elements and thethermostatically controlled control valve, and if appropriate theadjusting valve and the valve which controls the overall heating-watervolume flow, can be arranged in a common valve block, which has oneoutput at which the first and second parts of the heating-water volumeflow are combined with one another, and which is connected to the panelheating.

The invention will be explained in more detail in the following textwith reference to the drawings, in which:

FIG. 1 shows a first embodiment of the control system with the volumeflow elements permanently set,

FIG. 2 shows an embodiment of the control system in which the volumeflow elements can be varied,

FIG. 3 shows a further embodiment of the control system in which thevolume flow elements can be varied.

FIG. 1 shows a first embodiment of the control system.

In this embodiment of the control system, the outlet of the adjusting orshut-off valve 10 is connected to a valve 6 which splits the overallheating-water volume flow 1 from the inlet into two heating-water volumeflow elements 2, 3, of which one volume flow 3 is supplied directly tothe panel heating 11, which is connected to the heating-system return12. The valve 6 is in this case formed by a shutter, which results in afixed ratio between the two flow elements 2, 3 of the heating-watervolume flow 1. The volume flow element 2 is likewise supplied via athermostatically controlled control valve 4 to the inlet of the panelheating 11 which, for example, is floor heating. In this embodiment, theratio between the two flow elements 2, 3 of the heating-water volumeflow 1 is therefore predetermined, and is fixed, by the design.

In contrast, in the embodiment shown in FIG. 2, the valve is formed by avalve 5 which can either be operated from the outside or is remotelycontrollable. The function of this valve 5 is the same as in the case ofthe embodiment shown in FIG. 1, but with the capability to adjust theratio of the volume flow elements 2, 3 in this case. In this case, theproportion flowing via the thermostatically controlled control valve 4may be varied either towards 0 or towards 100%.

The proportion of the second volume flow 2 should become greater, thegreater the extent that disturbance variables, such as external heat,solar radiation, the direction of the sky, etc can influence theenvironment in the individual room.

Changes can be made later by a change in the user behavior, resulting ina change in the setting ratio.

The reference variable or controlled variable which controls the drivefor the valve 5 or 7 is a different variable than that for the drive forthe valve 4. The drive for the thermostatically controlled valve 4 maybe a thermostatic remote sensor, an electrical actuating motor or a timeswitch.

The hydraulic matching, that is to say the setting of the overallheating-water volume flow 1 in order to cover the heating load for theroom, is achieved by operating the valve 10. This allows the overallheating-water volume to be shut off at the same time. Although thedrawings show this valve 10 in an arrangement upstream of the valves 5,6, it may also be connected downstream from these valves.

In the embodiment shown in FIG. 3, the same valve 6 is used as that inFIG. 1 with a fixed shutter (although it is also possible to use thevalve 5 as shown in FIG. 2), but a variable valve 7 is arranged in thepath of the first volume flow element 3, allowing adjustment of thisfirst volume flow element.

The reference or control variables which control the drive for the valveare the surface temperature of the floor or the flooring temperature(state of charge), or the temperature of the heating medium.

According to one preferred refinement of the invention, all of the valveelements 10, 5/6, 4, and if appropriate 7, shown in FIGS. 1 to 3 arecombined to form a single valve block, which is connected on one side tothe inlet and on the other side to the panel heating, so that there isno need for the extensive distribution systems that are otherwise usedfor panel heating systems in dwellings, and these can be replaced by asingle ring main or spur-line system.

The arrangement in a common valve block means that the valve cones ofdifferent valves, such as the valves 4 and 7, can be operated by acommon spindle, for example the spindle of an electrical control drive,by combined measurement and control commands, or for frost-protectionand emergency-operation settings.

1. A control system for panel heating, in which a valve is provided inorder to control the heating-water volume flow through the panel heatingin a room, wherein the valve is preceded or followed by a valve whichsplits the heating-water volume flow that is supplied to the respectiveroom into two parts, with the first part of the heating-water volumeflow being supplied directly or via a restrictor device to the panelheating, while the second part of the heating-water volume flow issupplied to the panel heating via a thermostatically controlled controlvalve.
 2. The control system as claimed in claim 1, wherein the valve isdesigned to adjust the proportional components of the first part of theheating-water volume flow, which is supplied directly to the panelheating, and of the second part of the heating-water volume flow, whichis supplied via the thermostatically controlled control valve.
 3. Thecontrol system as claimed in claim 2, wherein the valve has a fixedsetting for the proportional components of the first and the second partof the heating-water volume flow.
 4. The control system as claimed inclaim 2, wherein the proportional components of the heating-water volumeflow can be adjusted by means of the valve.
 5. The control system asclaimed in claim 1, wherein the valve has a fixed shutter which governsthe second part of the heating-water volume flow which is supplied tothe panel heating.
 6. The control system as claimed in claim 4, furthercomprising a further adjusting valve for the first part of theheating-water volume flow is arranged between the valve and the inlet ofthe panel heating.
 7. The control system as claimed in claim 1, whereinthe valve is remotely controllable.
 8. The control system as claimed inclaim 1, wherein the valve is an adjusting or shut-off valve forhydraulic regulation of all of the panel heaters in a heatinginstallation, and precedes or follows the valve.
 9. The control systemas claimed in claim 1, wherein the valve, the valve and thethermostatically controlled control valve as well as the adjusting valveare arranged in a common valve block, which has one output at which thefirst and second parts of the heating-water volume flow are combinedwith one another.